--- /dev/null	2018-11-02 14:35:10.064842917 +0100
+++ new/src/hotspot/os_cpu/linux_x86/gc/z/zArguments_linux_x86.cpp	2018-12-19 12:55:51.088826327 +0100
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArguments.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/globals_extension.hpp"
+#include "utilities/debug.hpp"
+
+void ZArguments::initialize_platform() {
+  // The C2 barrier slow path expects vector registers to be least
+  // 16 bytes wide, which is the minimum width available on all
+  // x86-64 systems. However, the user could have speficied a lower
+  // number on the command-line, in which case we print a warning
+  // and raise it to 16.
+  if (MaxVectorSize < 16) {
+    warning("ZGC requires MaxVectorSize to be at least 16");
+    FLAG_SET_DEFAULT(MaxVectorSize, 16);
+  }
+}